1. Field of the Invention
The present invention relates to a communication apparatus for voice data, image data, code data or the like, and more particularly to a communication apparatus connected to a communication network having a function to transmit information for discriminating a calling party.
2. Related Background Art
A conventional analog telephone network is not provided with a function to notify a called party of information for discriminating a calling party, e.g., a telephone number of a calling party. An integrated Service Digital Network (ISDN) can transmit a discrimination number of a calling party to a called party. As an example of utilizing such a discrimination number, there has been proposed to display the calling party telephone number received from the network on the called party terminal equipment. The present applicant has filed U.S. patent applications Ser. Nos. 151,309, 283,857, 283,852, and 307,506 relevant to the ISDN.
The above-described terminal equipment connected to the ISDN simply displays a calling party number. Therefore, an operator knowing the number can only discriminate the calling party. From this point of view, display of the calling party number does not give any particular advantage over a conventional analog telephone network.
Even with such display under the ISDN service, a user must mentally prepare for responding to an optical calling party. In addition, if terminal equipment is used by a plurality of persons, since only a person knowing the number can discriminate the calling party, an unknowledgeable person may respond to the call unnecessarily, thus posing a problem of wasteful call response.
The connection method used by an exchange such as a private branch exchange (PBX) or a key telephone set (KTS) includes a call reception ringing method which connects a call to each extension within the service area and a call reception transfer method which transfers a call to another office line. The present applicant has filed U.S. patent applications Ser. Nos. 270,208 and 250,222 in connection with KTS.
As the call reception ringing method for PBX and KTS by which, upon detection of a call from the external line, it is determined which extension or extensions are to be rung, there are a concentrated call reception method and a distributed call reception method. With the former method, a single extension is registered previously for each external line accommodated within an exchange so that the inner lines can be controlled based on the external line receiving a call. With the latter method, a call is distributed to a plurality of internal lines previously designated for each external line. There is also known a dial-in service whereby a call is sent to a single internal line in accordance with a selection signal received from a central office after detection of a call.
With the known call reception transfer method, call reception is temporarily suspended, and after another external line is established, a predetermined telephone number is sent via the established external line. After detecting a response from the external line, it is connected to the suspended call reception external line to conduct speech communication.
The above conventional methods do not suggest to discriminate a calling party. Therefore, in the distributed call reception method, for example, a plurality of extensions previously registered are rung, which extensions will include those not associated with the calling party.
Further, in the call reception transfer method, a call is transferred to a transfer destination previously registered irrespective of who is the calling party. Therefore, an unnecessary call is transferred to the transfer destination telephone which is rung wastefully.